BOSSASO (Reuters) - Somali pirates are suspected of hijacking a bulk carrier ship, the head of a maritime security company said on Saturday, in the latest in a string of attacks after years of calm.

A security source working at the Puntland Marine Police Force said the vessel was Tuvalu-flagged and is known as OS35.

Graeme Gibbon-Brooks, the head of private company Dryad Maritime Intelligence, said industry sources had confirmed the hijacking.

The United Kingdom Maritime Trade Operations (UKMTO), which coordinates shipping in the Gulf of Aden area, said on its website it had received a notification earlier on Saturday from a vessel in an area in the Gulf of Aden that was under attack and may have been boarded.

"Vessels transiting the area are advised to exercise extreme caution," UKMTO said, without giving more details.

The hijacking comes days after pirates hijacked an Indian dhow that was on route to Bossaso from Dubai.

Somali pirates hijacked an oil tanker in March, the first such seizure of a vessel since 2012, but released it after a clash with the marine force in Puntland.

Shipowners have become less wary of piracy after a long period of calm off the Horn of Africa, experts say, and some have started using a route known as the Socotra Gap, between Somalia and Socotra Island, to save time and costs. The route is considered riskier than others.

<^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Graphic of attacks by Somali pirates since 2008: